I'd vote for a proper shovel, not a folding one. Better reach, better lifting of the sand, easier on your back, more useful for other tasks, money better spent, probably longer lasting, and generally more efficient. If you have the room in your vehicle, use it.
If this is only ever to be used in sand, you probably want a square headed shovel because they move more with each scoop. If the shovel will see mixed use in sand and rockier soils then get a round nose shovel. Just my $.02 and I've literally dug thousands of holes all over North and Central America by hand in all kinds of soils.
On my vehicle I carry a short, T-handled, round nose shovel for recovery and a file to keep it sharp.